Method of scrubbing



M r 8, 1944- G. c. SCHAUFFLER ETAL 2,345,294

' METHOD OF SCRUBBING Filed Nov. 13, 1939 3 Sheets-Sheet l INVENTORS:GOODRICHC'SCHHUFFLER BY DBERT OSHOEMA F? M r h 28, 1944. 6.2;.Sal-MUFFLER Em 2,345 294 METHOD OF SCRUBBING Filed Nov. 13, 1939 3Sheets-Sheet 2 F IG. 7 INVENTORS; GOODPICH C SCH/7UFFLER w w w w. w m um zetuamut kzwumum 56 75 1101! 1213 MINUTES SCPUBBED March 1944- v G. c.SCHAUFFLER ETAL 2,345,294

METHOD OF SCRUBBING Filed Nov. 13, 1939 *3 Sheets-Sheet 3 n-u CF-555.,

- INVENTORS; GoomlcHC. SCH/IUFFLER Patented Mar. 28, 1944 METHOD OFSCRUBBTNG Goodrich C. Schaufller and Robert C. Shoemaker, Portland,Oreg.

Application November 13, 1939, Serial No. 304,034

6 Claims.

This invention relates to a method of cleansing or scrubbing, and hasspecial reference to the washing of the hands and arms.

The invention is of special utility in hospital scrub rooms andbacteriological research laboratories, and has utility wherever there isa necessity to clean or sterilize the hands and arms, as in kitchens andother places where food products are handled or treated, and in machineshops and similar places where the hands and arms are particularlysoiled.

The conventional practice in washing the hands, where the operation isto be done thoroughly, is to scrub them alternately, using one hand toscrub the other. In the case of surgeons it is generally necessary tocleanse the hands thoroughly by scrubbing at least once every day and,on occasion, many times a day. Accepted practice demands that this scrubbe not less than seven nor more than ten minutes in duration, whichprocess is time consuming, fatiguing, nerve wracking and often damagingto the hands. It is the custom to hold a brush in one hand and scrub asmuch of the surface of the back of the other hand as can be contacted atone time. Eventually the entire area of the back of the hand is covered.The hand is then turned and the palm scrubbed in the same manner.Interstices between the fingers are thereupon carefully scrubbedindividually, then the under surface of each nail is carefully scrubbed.The wrists and each surface of the forearm are then scrubbed, a smallportion at a time. When one hand and arm have thus been completelycleansed by scrubbing, the brush is shifted to the clean hand and theprocess is repeated on the other hand and arm.

No attempt is made to allot given time intervals to particular surfaceareas, and each operator carries out the procedure according to his ownconcept of effectiveness. For example, surgeons of long experience, aswell as relatively inexperienced interns, scrub their hands without anydefinite or accepted standard of effectiveness. A muscular, nervous,high strung individual tends to scrub at high speed under great tension,moving rapidly, covering large surfaces with each stroke of the brushand using high pressure. Languid, lethargic individuals daub small areasof either hand with a disinterested and ineffective touch. As a resultof this lack of uniform procedure, a uniform standard of cleanliness, orfreedom from bacteria, is not ordinarily attained,

maining on the hands is shocking when revealed by test.

The necessity of prolonged scrubbing by the conventional method Justdescribed is not established upon a scientific basis, althoughconsiderable fairly well controlled scientific research indicates thatthe ten minute period leaves some margin of safety for everyone. Howmuch less than ten minutes might safely be used for scrubbing by theconventional method has not previously been established. A study of thelack ofuniformity, and the many uncontrolled variable factors in theconventional method indicate why there is little or no dependablebackground of scientific research. The reason is that the lack ofstandardization of variables in the present scrubbing practice is somanifest that its use to establish scientific results is grosslyunsatisfactory and unreliable. In other words, present methods are sounreliable that bacteriological studies based upon them must beconsidered unsound.

Analysis indicates that the important variable factors are: (a) speed ofbristle movement; (b) pressure exerted upon the skin by the bristles;(c) extent of surface covered by each stroke; (d) scrubbing time. Thegross irregularity of these factors in various individuals is at onceobvious. Because of these many variables it is diilicult .to use thepresent method to evaluate itself to actually determine its owneffectiveness.

The object in general, therefore, of the present invention is to providea method whereby a better controlled and more uniform result thanheretofore obtainable may-be accomplished in washing and scrubbingthehands, through accurate control. and standardization of the speed ofthe bristle movement, the pressure exerted upon the skin by thebristles, and the extent of the surface covered by the stroke.

- Particular objects are: (1) to improve the final hand sterilizationresult; (2) to decrease the time and effort involved in obtaining thedesired result; (3) to achieve uniformity of result in differentindividuals; (4) to indicate and record the amount of effort and thusthe relative effectiveness of each individual scrub; (5)- to establish areliable means of studying methods of hand sterilization; and (6) tofacilitate the preparation of standards whereby individuals may becatalogued as to relative contamination by dangerous hand bacteria.

- The present invention not only facilitates clinical procedure, butalso offers ameans of standand in many cases the amount of bacteriareardizing methods of study and achieving accu,

rateness in the study of hand sterilization. Instead of wasting valuablenervous energy in actual scrubbing, standing and bending prior toentering the surgery, an operator using the machine of the presentinvention will be comfortably seated in a chair facing the scrubbingdevice. Above the machine is framed a simple, diagrammatic, illustratedinstruction chart. On this chart the scrubber is shown successivepositions of the hands .and arms, and the precise amount of energy to beapplied in each of those positions. Bristle pressure is registeredindirectly in the form of applied energy on a recording dynamometer. Aclock or special timing. device, or the time indicator on the recordingdynamometer, may be used to'time each position. The operatoraccomplishes at complete ease, without any concentrated attention onthis part, the following functions: Instead of one small surface of onehand, there is scrubbed simultaneously both surfacesof both hands.interdigital space or one or two nail beds, there are scrubbed several,01'' all, at the sametime,

all being treated with a uniform bristle speed and.

pressure. Regardless of the operators experience in scrubbing, andirrespective of his individual temperament, the scrubbing will beaccomplished on all operators by a scientific, almost identical,process. The standard of cleanliness willbe substantially the same forthe experienced surgeon, the inexperienced interne, and the-listless. or.conscienceless operator.

These and other advantages of the invention will becomeapparent to oneskilled in the art as the disclosure proceeds in connection with thedrawings, in which:

Figure 1 is an elevation chine embodying the principles of the presentinvention. I

Figure 2 is a plan view of the machine shown in Figure 1. a

Figure 3 is a perspective view of the machinev modified form the linechineemploying revolving brushes. Upon a. base.

I are.supported'thewertical. columns 2' and Fixedly secured to the lowerportions of columns 2 and 3 are bearings 4, inwhich is journalledthelower shaft or mandrel 5. Keyed to the mandrel or shaft 5 arebrushes-such as illustrated at 5, 6, 6. The brushes may be retained onthe mandrel by means of a knurled nut i. The. opposite end of shaft 5carries a spiral gear 8 keyed thereto. Slidably mounted on, the verticalcolumns 2 and 3 above the fixed bearingsl are bearings .9v joined by;the web ID. Thebearings 9 carry the. upper shaft or. mandrel H, on whichare mounted brushes 6, 6', 6 etc., in a manner similar.- to the. brusheson thelower shaft. Likewise, the opposite end of shaft ll carriesspiralv gear 12 keyed thereto. A bearing l3 on the base, and a bearing14. supported and heldv in. alignment by the columns 2 and}. hold theshaft [5 forv rotation. Fixed to thetlowenportion of said shaft l5, seasInstead of one view of a scrubbing ma-;

to rotate therewith, is the spiral gear l6 in engagement with the spiralgear 8. Keyed to the shaft l5 and free for longitudinal movement thereonis the upper spiral gear I! retained between fingers I8 and [9 on anextension of the web I0. An electric motor 29 secured to the base Ifurnishes the motive power, driving the shaft 5 through the reductiongear 2|.

Means is provided for vertically adjusting the upper shaft II to varythe spacing between the opposed brushes 6 and 6". Various means may beemployed to provide this vertical adjustment,

' and other suitable means will occur to persons skilled in the art, butin the illustrated embodiment there is shown the cylinder 20, carried bythe bridge" 2-5, having therein a piston (not shown) and a piston rod 2|connected at its lower end to the web l0. Suitable fluid pressure meansmay be employed to operate the piston within the cylinder 20 in responseto pedal movement or other convenient manipulating device.

Extending upwardly from the bridge 25 is the. bracket 22 carrying. aspray pipe 231 for dispensing Water, soap solution, or other liquidconveyed by the tube 24. The pipe 23 may be provided with orifices inany suitable arrangement above the brushes 6. and 6.. Hot. and coldwater and a soap. solution may be fed selectively into the single tube24, under the control of foot or knee operated valves (not shown), orseparate tubes may be provided. The water valves should provide an.increased flow for rinsing the hands and brushes.

In the machine illustrated in Figure 1, the drive is such as. to producecounter-clockwise rotation of both sets of brushes, 6. and 6', whenviewed from the rig-ht hand ends of the. shafts 5 and II. It has beenfound. desirable to make both sets of brushes revolve in. the. samedirection so that the frictional forces tending to. pull the hand.- orarm, further into. the brushes balance the other frictional forces,tending to thrustv the hand or arm. out from between the brushes. Withthe brushes rotating in the direction described, theupper brushes 6'will tend to. pull the hand inwardly while the lower brushes 6' will.tendto thrust the hand outwardly, thus relieving. the operator of effortin holding his hand in the desired position, or of moving it from oneposition to another. In addition to having both sets of brushes rotatein the same direction, it is desirable that the upper brush rotate awayfrom the operator on its under side. If the upper brush rotated towardthe operator on its under side, the rotating bristles would snap waterdroplets onto the operator in anobjection-able manher. Withcounterclockwise rotation the revolving bristles on the lower brusheswill snap water droplets in the direction of the operator, but a shieldmay conveniently bearranged to protect the operator from Water comingfrom the lower brush. Suitable means should be provided beneath thebrushes to catch or carry away excess soap and water. a

It may be found convenient to provide brushes of variou shapes andcontours for cleaning different parts of the hands and arms, as forinstance, small, stiff brushes for cleaning around the-finger nails,thin brushes for cleaning between the fingers, and perhaps speciallygrooved brushes to allow complete insertion of the hand and forearm.However, the arm may be inserted between the cylindrical brushesillustrated by appropriately raising the. upper brush.

The speed of rotation should be sufficient tokeep the brushes saturatedwith water entirely around their peripheries, but insufficient to spinthe water off by centrifugal force. Experimentation shows that at speedsabove a certain minimum, the liquid will distribute itself annularly ina substantially uniform layer nearthe ends of the revolving bristles,and will not tend to collect at the bottom side of the brush,'nor todrip therefrom. When the brush is revolving at the proper speed, thewater and soap will be carried around with the brush until it contactssome foreign object such as the hand or arm to be washed. A portion ofthe .liquid will thereupon be transferred from the revolving brush tothehand, or arm, andthewater flow from spray pipe 23 should be adjusted tosupplyv only the rate of flow desired for washing. When the hand or armis not in contact with the revolving brush, the water will remaintherein, unless the flow from pipe 23 is allowed to continue, causing anexcess over the capacity of the brush. It is intended that a foot valveor'the like be allowed to close, stopping the water flow from pipe 23,when the hands are removed from the brushes. When the brushes are idlingat the proper speed, the water will be retained as described, and if therotational speed should be reduced, or the brushes stopped entirely, itwill be noted that a considerable quantity of water will flow from theunder sides thereof. Also, if the brush speed be increased, centrifugalforce will overcome capillary attraction, and the water will spin offtangentially in all directions. Neither of these last mentionedconditions is desired for performing a satisfactory washing or scrubbingoperation.

Proper control of speed prevents wasting of the soap, in that thebrushes can be kept continuously saturated with soap and water by addingthrough the spray bar only the quantity required for use on the hands.The actual optimum speed for a given installation depends upon theabove-discussed considerations, and it is held within the scope of thisinvention to vary the diameter of the brushes as desired, as well as tovary their form, in order to best satisfy the requirements of variousscrubbing conditions.

In using the machine of Figure 1 the hands may be inserted fiatwisebetween the brushes and the relative spacing of brushes 6 and 6'adjusted by means of fluid pressure in the cylinder 20 to give thedesired scrubbing effect. As the hands or arms are progressivelysubjected to scrubbing action and the thicker parts of the forearm areinserted between brushes 6 and 6', greater spacing will be required todevelop the same scrubbing action without undue abrasion to the skin.Cleansing of the finger nails and the adjacent surfaces of the fingerscan be accomplished by appropriate technique with the particular kindsof brushes employed, the pressure against the brushes being controlledby the operator either by applying the fin-- ger directly to one of thebrushes alone, or by means of the cylinder 20, if the hands are betweenthe two brushes. 6 and 6', so as to obtain a satisfactory scrubbingoperation.

To determine and measure theamount'of work being done in the scrubbingoperation, a dynamometer is provided. The dynamometer will in dicatewhen the scrubbing is being conducted sufilciently vigorously and willalso givereadings which may be compared with a standard of satisfactoryoperation. Thedynamcmeter may be of any type'kncwn in the art, and maybe either an electrical ora mechanical type. In conducting experimentalwork, the dynamometer, in addition to indicating continuously the workbeing done in the scrubbing operation, should also preferably make agraph or record of such work or energy output. These records would beespecially valuable in bacteriological research in establishing definitebasis of comparison of the cleanliness, or freedom from bacteria, of thehands, as a fundamental starting point for experiments.

In the preferred embodiment, an electrical dynamometer 26 of therecording type is connected into the electrical supply for the motor 20.The movable arm 21 responds to the power input for the motor 20, tracinga power curve on the graph 28, which revolves at a speed such thatdivisions thereon may be calibrated in minutes. Power may be indicatedin any suitable units. The units of work expended in any scrubbingoperation will then be represented by the area under. the power curve, adatum line being established to'represent the amount of power requiredto run the machine when no scrubbing is taking place.

The embodiment shown in Figures 4 and- 5 Bar 36 is slidably supported inthe bearings 34* and 35 for limited horizontalmovement. Bar 36 carrieson one extremity the removable brush 31 attached by wing nut or othersuitable clamping means, as indicated at 38., Depending from the bar 36is the projection 39 for purposes presently to be described. Between thebearings 34 and '35 the rod 36 is provided with an eye or Scotch yoke 40to receive a crank 4| extending upwardly from the gear reduction box 42on the motor 43. Motor 43 may conveniently be bolted to the base 3|. Bar36 carries at its other extremity the rack 44 offset in the mannershown.

The upright columns 32 and 33 also carry the slidable bearing blocks 45and 46. Bar is mounted for limited horizontal sliding movement in thebearing blocks 45 and 46, said bearing blocks being held in alignment bythe integral web 48. Bar 41 carries a brush 49 at one extremity thereofdetachably secured in any suitable manner,- as is the lower brush justdescribed. The upper brush 49 may be provided with bristles on bothfaces as illustrated, if desired, or may consist of two brushes, back toback. The contour of the bristles on either or both faces of the brush49, as well as the bristles on the brush 3'l,'may be either flat orcurved as best suits the requirements of the objects to be scrubbedthereby. It is also within the scope of this invention to substitute foreach of the brushes 31 and 49 a plurality of small brushes of a sizereadily obtainable at small cost, and the brush holding means should beadapted to receive either the small or the large brushes. Bar 41terminates at the end opposite the brush in a rack 50 similar to therack '44, but ofiset in the opposite direction.

, A vertical shaft 5| is carried by lower and upper bearings 52 and 53,respectively. and .carries the gear'sector 54 fixed thereto. Gear sector54 engages the rack 44 so that reciprocation of the bar 36 willoscillate the shaft 5|. Slidably keyed, on the upper part of the shaft5!, as by the keyor spline 56, is the gear sector 55 retained betweenthe fingers 51 and 58 extending from .web 48.

21h g g s 5? an a omi r m F re for cl'earness. Gear sector 55 rotateswith gear sector 54 to impart a reciprocating motion to bar 41-simultaneously with. and in a direction opposite to the reciprocatingmotion of bar 38. To adjust the spacing between the brushes 3'! and 49the fluid cylinder 59 is provided, having a piston rod 50 operativelycontrolling the height of web 48- as described in the species shown inFigure 1.

A bracket Bl extends above them-achine to support one or more pipes 62.which may be drilled tosupply liquid from the hose 63 as in Figure 1.

In the embodiment shown in Figures 4 and 5- an additional set of brushesis provided having a spiral movement, these being particularlyadvantageous in scrubbing between the fingers. The spiral scrubbingbrushes are shown at 64 and may be removable. from their mandrel's aswere the brushes described in Figure 1. Knurled nuts 65 are illustrativeof one means for retaining the brushes. fixed on their respectivemandrels. Brushes. are rotatably carriedby bearings 66 in the. dependingprojection 3-9 in such a manner that there is noaxial or lengthwisemovement of the brushes with respect to member 5d. The shafts ormandrels for the brushes 64 extend through and. beyond the bearings 66-and are provided on said extensions: with spiral threads or grooves 61.Anupstanding member 68 is rigidly secured to the base 3| and contains athreaded opening to cooperate with each threaded spiral 61; In thismanner, reciprocation of the projection 39 on the bar 36 will impart alengthwise reciprocating movement to the brushes 54 and atthe same.time. cause them to oscillate so as to produce a spiral scrubbing orbrushing motion. A removable guard 69 may be provided to steady the handof the operator.

The machine illustrated in Figure 4 performs a scrubbing operationbasically in the same manner as the machine in Figure 1, except that thescrubbing motion on the: hands is imparted by reciprocating brushesinstead of revolving brushes. The motor 43 operates through thereduction gear, crank, gear sectors and racks, illustrated anddescribed, to move the brush 3T horizontally to the right as the brush49 is simultaneously moved horizontally to the left, and vice versa.,Freedom of access to the brushes 3! and 49 may be obtained either fromthe front or from the right of. the machine as viewed in Figure 5. As inthe case of the revolving brushes of Figure 1, the hands, may beinserted between, the opposed brushes, and the opposite surfacesscrubbed,v thereupon advancing, the hands to presentthe forearms on thevarious surfaces to the brushing action progressively. The spacing btween the brushes 3! and 49 may be varied continuallyduri-ng thescrubbing. operation by the fluid pressure cylinder 59 to maintain thedesired application of pressure. on the skin.

In Figure 4 the small brushes 64- are especially eflicacious forcleaning between the fingers and for cleaning under the finger nails. Asdescribed, the reciprocating, movement. of the lower brush causes acombined reciprocating and oscillating movement of brushes, 64. If theoperators hand is steadied against the guard 69 to hold the handstationary, adjacent surfaces of the fingers inserted between thebrushes will be subjected to a reversing, spiral scrubbing action. Whilethe brushes B4 are illustrated as beingv cylindrical, other, shapes maybe used if desired.

If desired, the main brushes 31 and 49 may be made to oscillate-as theyreciprocate, in the same manner as brushes 64, to give a' spiralscrubbing motion. Cylindrical brushes might then be used, similar to thebrushes 6, 6 of Figure 1. Other types of scrubbing motions, and othertypes of scrubbing members may be used in carrying out the spirit ofapplicants invention. For instance, the scrubbing members may be carriedon juxtaposed endless belts, as illustrated at 8|, in Figure 6', orrevolving discs, adjustably spaced so that a part of the body, such as ahand, may be scrubbed simultaneously on both sides. It is not necessarythat the scrubbing members he bristle brushes as rubber projections maybe substituted for animal bristles, or the scrubbing surfaces may beformed of sponge or crepe rubber, or other material suitable forproducing the desired scrubbing action. In practice, the sterilizationrequirements will constitute a major consideration in the choice ofsuitable scrubbing members. a

A dynamometer device may be applied to the machine of Figure 4 asdescribed in connection with the revolving brush machine of Figure 1. Itis desired to indicate and record thework performed in the brushingoperation in the same manner as described in connection with the machineemploying revolving brushes.

With either typeof machine a routine laboratory procedure may bedeveloped to establish a standard of cleanliness, or freedom frombacteria. This standard may be used not only as a guide for minimumscrubbing time for surgeons and interns about to enter the operatingroom, but is also of the greatest utility in forming a basis forstatistical comparison in the performance of bacteriological research.The method of this invention will materially assist in reducing to aconstant one of the annoying variables in hand sterilization forsurgery.

For the purpose of obtaining a quantitative analysis, the followingprocedure was prescribed by and the Work carried out under th directionof the University of Oregon Medical School, Department of Bacteriology.

(a) Scrub hands and forearms vigorously for one minute with sterilebrush in sterile water and sterile basin using no soap.

(b Scrub same areas immediately thereafter in prescribed method to betested (i. e., manually for n minutes or with machin for 11. minutes).

(0) Repeat (a) for one minute with new sterile brush and water.

(d) Plate out samples of Water from (a) and (c) in usual mannerprescribed by bacteriological practice and count for organisms afterfortyeight hours incubation.

(6) Using difference between count from (a) and (c*)' as numerator andcount from (a) as denominator calculate reduction in percent. Thisresult is referred to below as "Percent Reduction.

This quotient appears to represent the nearest possible approach to anindex of scrubbing efficiency as it is not possible to actually countthe bacterial flora on the hands at any given time, i. e., before orafter scrubbing in accordance with the method to be tested. In this waythe minimum of time required to reduce thev bacteria count to asatisfactory figure may be determined, and a standard established. Thisprocedure also serves as a basis of comparison for the various handwashing techniques of different individuals using the, conventionalscrubbing brush method, as a basis for comparison of the machine methodversus the conventional method, and as a basis of comparison betweenvarious antiseptic solu- Percent reduction Time scrubbed in minutesManual Machine method method Whereas from a scientific point of view wedo not contend that the obvious conclusions from these tests areabsolute, we submit that they have been conducted in a scientific andimpartial manner and that claims have been presented in a manneractually more conservative than the general indications. Considering thelarge number of tests conducted, it can be stated categorically that theimprovement of the machine over the hand method is established. Furthertests will be necessary to establish beyond question the degree ofimprovement.

It will be seen from the tabulation above, and. from the curves inFigure 7, that the machine method of removing bacteria from the hands isconsistently superior to the manual method, within the time limitstested. The advantage is of diminishing magnitude as the time increases,and would probably vanish at about twelve or thirteen minutes. Theadvantage of the machine method is very marked when the scrubbing timeis brief, and would appear even more striking if the manual method curvehad been made to pass through the two minute and three minute points.The flattening out of both curves as the time increases indicates thatin ten or twelve minutes the greater part of the bacteria that can beremoved have been removed. Therefore, if time is not considered, itcannot be contended that the machine does a more thorough job, but it isevident that in any given reasonable time the machine will do a betterjob, or, will attain a given result in less time.

The saving in time appears to average 33% of the manual time, varyingfrom 42% at 30% reduction in bacteria count, to 28% at 70% reduction inbacteria count. This is demonstrated by the following tabulationprepared by taking values from the smooth curves of Figure 7:

An important conclusion to be drawn from Figure 7 is that the presentmachine method'described herein appears to produce more uniform resultsthan the conventional manual method. ihis is evident from the fact thata smooth curve is easily drawn through, or very hear, all the pointsplotting "machine results, whereas the curve for manual results is acompromise throughoutmost of its range. It is assumed that both curvesshould be smooth lines by the nature of the experiment, and thata curvethat-attempted to'. include allthe points of themanual results would notbe as near the'truth as the curve drawn.

The advantages of this invention have been pointed out with particularreference to the requirements of surgeons and laboratory technicians,but they are present in varying degrees to other classes of persons whoare required to vigorously and efficiently scrub their hands at frequentintervals, and it is to be understood that this invention is not limitedto use in the surgery or laboratory, but that it may be used wherever ascrubbing operation is to be performed.

Having now described the principles and method of our invention and inwhat manner the same be used, what we claim as new and desire to protectby Letters Patent is:

1. The standardized method of cleansing a part of the human body whichcomprises applying a scrubbing action to said part and applyin pressureto said part by said scrubbing action, continuously measuring the energyapplied during said scrubbing action, varying said pressure to obtain a,predetermined application of energy in said scrubbing action andcontinuing said action until said measurement indicates the xpenditureof energy of a predetermined value.

2. The standardized method of cleansing a part of the human body whichcomprises subjecting said part to a scrubbing action, measuring the rateof expenditure of energy in said scrubbing action, continuing saidaction until said measurement indicates the expenditure of energy of apredetermined value, and simultaneously making a graphic record of saidrate of expenditure of energy and also of the amount of work done insaid scrubbing action.

3. The standardized method of cleansing a part of the body whichcomprises simultaneously applying a scrubbing action with pressureagainst opposite sides of said part, continuously measuring the totalenergy applied to said scrubbing action, varying said pressure to obtaina predetermined application of energy and continuing said action untilsaid measurement indicates the expenditure of energy of a predeterminedvalue.

4. The method of cleansing the hands and forearms which comprisessubjecting said parts to the scrubbing action of complementar scrubbingmeans, pressing the said parts between said scrubbing means until therate of energy expenditure due to frictional resistance between saidmeans and said parts reaches a predetermined value, measuring the amountof energy expended in the scrubbing action, and continuing said actionuntil said measurement indicates the expenditure of energy of apredetermined value.

5. The method of cleansing the hands and forearms which comprisesproviding a pair of complementary scrubbing elements, supplyin cleansingmaterial to said elements, inserting said parts between said elements,adjusting the pressure of said elements against said parts until thetherefrom by centrifugal force, inserting the hands and forearms betweensaid brushes, ad-

justing the pressure of said brushes against the I hands and forearmsuntil the rate of energy expenditure due to frictional resistancetherebetween reaches a predetermined value, measuring the amount ofenergy expended in the scrubbing action, and continuing said actionuntil said measurement indicates the expenditure of energy 19 of apredetermined value.

GOODRICH C. SCI-IAUFFLER. l ROBERT C. SHOEMAKER.

